In magnetic resonance imaging (MRI), nuclear magnetic resonance (NMR) signals given off by protons in the presence of a strong magnetic field are detected after excitation by a radio frequency (RF) signal using antennae termed “RF coils”. Generally speaking, there are two types of RF coils: whole body RF coils, which are used to image large segments of a patient, and “local” or “surface” RF coils, which are configured to image specific anatomies of interest, such as the knees, shoulders, neck, breasts, hands and head.
Whole body RF coils are typically provided with commercially available MRI imaging systems. These RF coils provide a large field of view to accommodate, for example, the chest and abdominal regions of a human subject, and as a result, their fields couple to large amounts of tissue outside the region of interest being imaged. Because of the large field of view, the signal to noise ratio (SNR) of the signal in the anatomy of interest is relatively high, and quality factor of the RF coil is low.
Local RF coils are reduced in size and designed to couple solely with tissue in the region of interest. Local RF coils, therefore, are typically positioned as close as possible to the anatomy of interest, and limit the field of view of an MRI scan to the selected region. The result is a significantly improved SNR and quality factor, and a reduced image size that provides higher resolution of the area of interest.
To provide high resolution images of selected anatomy at high SNR, it is increasingly common to use a number of local RF coils simultaneously in parallel imaging techniques. In these techniques, images are acquired from multiple receive channels, for example 8, 16 or 32 channels receiving signals from 8, 16 or 32 RF coils respectively. In a typical multiple coil array arrangement, for example, several adjacent coils are provided for receiving signals during imaging. Coil switching, multiplexing, or dynamic coil selection strategies are used to optimize a subset of coils for imaging of anatomies of a smaller volume, or to switch between areas of interest during the image acquisition or imaging procedure.
To facilitate these parallel imaging techniques, there is a need for a device that allows an operator to position various types of RF coils adjacent an anatomy of interest while in the bore of a MRI scanner. Such a device should further facilitate connections between the MRI scanner and the RF coils, and allow for circuitry to switch between the coils. The present invention addresses these issues.